How to seal painted wood for outdoor use? 7 simple steps to achieve a perfect result

Painting outdoor furniture can be quite tricky. You have to think about protecting wood, so the paint lasts longer. Sealing painted wood might be an option. It protects the wood surface from extreme weather conditions such as rain or direct sunlight and gives your project a nice finished look. The wood that has been sealed, tends to keep its original appearance for way longer.

This article will teach you how to seal painted wood for outdoor use. We will tell you about different sealants and which one you should pick for your painted wood projects. Following our guide, you will be able to apply sealant fast and efficiently, so the result will be satisfying. Let’s start!

Why should you seal painted wood?

We must say it is not compulsory to seal painted wood because nowadays, exterior paints contain some kind of protection for the wood.

If you choose a decent acrylic paint, for example, it can last a few years without cracking or cheeping off.

Sealing painted wood though will definitely keep your project safe, no matter what weather is outside. Sealing will be necessary if you live in an area with a climate that changes often.

Living closer to the ocean, for example, will result in humid air around, which can impact the top layer of wood surfaces.

Wood sealant ensures no water gets into the wood, and it also protects against harmful UV rays, and all types of damage and keeps the original beautiful finished look.

To summarize the advantages of having your painted wood surface sealed:

  1. Saving the original look of the painted wood. You can also pick the final coating to have some effects or to be a different color, which will change the whole appearance to be the way you want.
  2. Protecting from excess moisture, cracks, and scratches, keeping the stains away. These kinds of things can happen to outdoor furniture and the way to prevent it is by sealing it. Painted wood furniture will look the same a few years later. All you have to do is apply a wood sealer.
  3. Keeping mold growth away. Painted wood without protection can suffer from mold growing, causing the wood to rot. A wood sealer will not allow any water to get underneath.

When sealing painted wood isn’t required?

Sealing painted wood for outdoor use isn’t necessary in some cases. Check out the information below:

1. If your project has already been sealed previously.

If you applied sealant before, a new layer can be put in as long as you remove the previous layer. You have to use sandpaper and take the damaged top off the old sealant before you layer a new one.

If you do not know whether the surface has been sealed before, the easiest way to find out is by dripping some water on it.

After a couple of minutes, the untreated wooden surface will absorb water, whereas the one that has been sealed before will not.

2. If you have already used a top-quality water-resistant paint.

If you have invested in good paint, it already protects your painted wood from bad weather and makes it durable. If you try to layer a wood sealer on top of such paint, it will not be successful as it will not stick to it.

3. If you have implemented a design finish on your outdoor wood surface.

If you have some type of design on the surface, a wood sealer will ruin it. The standard effect the sealer provides is glossy. If you do not want such a finished look, do not use sealant.

In any other case, we strongly recommend applying a layer of sealant to keep the painted wood for outdoor use safe.

What types of sealants are there?

There are different kinds of wood sealers for painted wood you can find. Knowing the difference between them will help you to determine which one you will need based on your particular situation.

Exterior sealers

These sealers are perfect for wood for outdoor use. They have a unique formula to make the finish last, protecting painted wood from all sorts of damage.

Some of them also can be stretchy, adjusting to the environment due to the urethane compounds in their content. Exterior polyurethane is super durable and long-lasting.

You can also use an exterior varnish that essentially has all the same characteristics and just adds that high gloss look to the wood outdoors.

If the surface has been painted using water-based paints, you can try applying lacquer on top, which will act as a sealer.

Water sealers

Water sealers can be layered only on top of the surfaces that have been dried properly. Their main characteristic is being water-resistant.

Water-based polyurethane keeps exterior wood safe. Before purchasing any type of sealer, you have to be sure what type of paint is on your wood for outdoor use.


Wax-type of coating can withstand water. Choose one of the known brands to ensure the quality of the sealer is excellent, and the result will be satisfying.

The advantage of this type of sealer is that it can be layered on top of the existing coating.

How to seal painted wood for outdoor use?

Whether it is your first time applying a sealer on top of the painted wood for outdoor use or you have already done it before, the information below will be very helpful.

We will tell you what you have to take into account, what materials can be useful, and guide you through the whole process, step-by-step.

Safety measures

Wearing goggles that protect your eyes is essential. In any manufacturer’s instructions, you will find a recommendation to wear gloves as well.

Oil-based paints have a very strong smell, also the cleaning solutions are one of the strongest chemicals, so protecting your airways is a must. Use a face mask. Painting and sealing must be happening in an open, well-ventilated area.

Equipment and materials required

Start with selecting exterior polyurethane that will be suitable for your exterior paint. Trisodium phosphate will help you to prepare the surface. Any mineral spirits of your choice for cleaning the brushes is a must.


  • A brush
  • Sandpaper of different grit
  • A tack cloth
  • A bowl
  • One sponge
  • A pair of rubber gloves

A guide on how to seal painted wood

The below instructions will help you to successfully apply thin coats of sealant onto the wooden surface.

1. Cleaning the wood surface

The surface you are about to seal must be in perfect clean condition. Use a tack cloth and wipe anything that can affect the final result. The top layer has to be clean.

It is crucial to stay away from using a wet cloth as it will impact the paint job and ruin the whole plan. Cleaning is one of the most important parts of the entire process because the protective bond between the sealer and the paint depends on it.

If you have discovered some imperfections on the painted wood, you have to sort them out before you spray sealer.

2. Sanding the wood surface and wiping dust off

For the sealant to stick to the painted layer, it has to be smooth. Lightly sand the surface using a piece of sandpaper with fine grit. Pay attention to uneven spots.

The entire surface must be smoothed. Make sure you clean the remnants of the sawdust and paint, so nothing gets in the way. You can use a tack cloth again. Or vacuuming is also an option.

3. Sealer application

For latex paints or acrylic paints, pick polyurethane sealer. You can use anything to apply the first clear coat. It can either be a brush or a roller, or even a sprayer will do the job.

The waiting time between applying the next clear coat should be around four hours. It is not necessary, but if you sand lightly the surface between the coats, the chances of the perfect glossy finish are higher.

Usually, you will require two to three coats for the best coverage. Ensure each layer is completely dry before applying the next one.

4. Give it the time to dry completely

Once you have layered the last coat of sealer, leave it to dry properly. Do not use the wooden project until you can be sure it is dry. The time will vary depending on the kind of sealant.

If it is oily-based, it can take up to a week before you can start using it again. Do not rush, and wait patiently.

A new layer of sealant should be applied every five to ten years. Polyurethane finish will be lasting way longer than wax, for example. It will also depend on the type of wooden object and how frequently you are going to be using it.

5. Sanding polyurethane layer

As we previously said, you have to lightly sand each layer of sealant to ensure the perfect result. You should take a fine 320-grit sandpaper and smooth the whole surface in between the applications. The electric sander is a great help. If you have one, it can be used.

6. Cleaning the surface

Remove the dust and sealer particles before the next coating. Do not use a damp cloth. It has to be dry, so it doesn’t leave any moisture between the layers of sealant.

7. Applying additional layers of sealer

In order for the painted surface to last longer, apply multiple coats of sealant. The surface will be extra durable and will be able to withstand bad weather conditions.


What is the best sealer for painted wood outside?

If you want to protect painted wood from water, snow, or other type of damage, the best thing to do will be to use an oil-based polyurethane. If you want to take care of your painted deck or protect furniture for outdoor use, the oil-based sealer will provide superior protection, prolonging the lifetime of your projects.

Do you need to seal painted wood outside?

Sealing outdoor wood surfaces is highly recommended. It will help to keep the shiny appearance while protecting your painted surface from UV rays, water, and all sorts of scratches. It also depends on the type of paint you used. If it is an acrylic paint, you do not have to seal it because of its properties.

Waterproof paint also can keep your painted deck the way it looked after being freshly painted. Oil-based paint will need outdoor protection. So, using oil-based polyurethane or any of the oil-based sealers is advisable.

What can I put over the paint to make it waterproof?

If you want to keep water away from painted and bare wood surfaces, the way to make it water-resistant is by applying a few coats of clear sealer. For the protective glossy finish, you can use water-based polyurethane resins, solvent-based polyurethane, or any sealing varnish.

Polycrylic polyurethane is ideal for flat latex paint. So, conduct research before settling your mind on something.

Should I seal acrylic paint on wood?

We advise you to use a clear polyurethane topcoat, so your paint job is not a waste of time. Sealant is known for protecting wooden surfaces from harmful actions of UV rays, water, and other damage that can happen to the top coating over time. It allows you to enjoy the perfect finished look of your outdoor furniture or other wooden pieces.


Now you have found out how to seal painted wood for outdoor use the proper way with minimal expenses. You just have to pick the right sealer for the exterior paint you have. Exterior wood always needs extra protection to keep looking brand-new even after a few years. Harsh weather conditions, direct sunlight, and intense use affect painted finishes, which is why it is important to seal them.

If this information was helpful, please, share it with your friends and all the members of your family. If you still have any questions, leave them underneath this post, and we will get back to you!

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